Push-to-talk (PTT) refers to a half-duplex mode of communication during which a single user has mutually exclusive use of a wireless communication channel for the transmission of voice information to another user or group of users. From an operational viewpoint, originating party User A presses a PTT switch on a mobile device, possibly awaits a “ready” tone, speaks into a microphone of the mobile device, and then releases the PTT switch. At this point, a former called party User B can press a PTT switch, possibly await a “ready” tone, speak into the microphone, and release the PTT switch. This procedure is repeated with different parties becoming the originating user and transmitting to one or more called parties until the conversation has completed.
PTT service avoids the typical dialing and ringing sequence of standard telephony service and thus is quicker than standard telephony service. There is a time delay, however, between the moment that a user activates PTT service (usually indicated by pressing a PTT switch) and the moment a PTT circuit is set up (usually indicated by a “ready” tone). This time delay, known as the PTT call setup delay, is a critical parameter for PTT services. If the call set-up delay is larger than a user expects, the user may forget to wait for the “ready” tone and, instead, talk before the PTT traffic channel is set up. Talking before the PTT traffic channel is set up results in called users failing to hear at least part of the voice communications from the originating user, which results in an unfavorable user experience.
During a PTT circuit setup and teardown, a network's PTT radio resource controller passes through four fundamental states on a per-mobile basis. Initially, the PTT radio resource controller is in an idle state for a particular mobile device. When the PTT radio resource controller receives a communication request from that mobile device (e.g., a PTT switch is pressed on the mobile device, and the mobile device requests access on a signaling channel), the PTT radio resource controller goes to a busy state for the mobile device. The PTT radio resource controller next goes to a switch setup state when a radio channel is available, and the PTT radio resource controller goes to an active state when the PTT circuit setup is complete. While the PTT radio resource controller is in active state for a particular mobile device, that mobile device may transmit voice communications to one or more mobile devices over a PTT traffic channel. The PTT radio resource controller goes back to the idle state for that mobile device when the PTT traffic channel is no longer in use (e.g., there has been no activity on the PTT traffic channel for a predetermined period of time).
Because the PTT radio resource controller undergoes the same PTT circuit setup process for each mobile device, the average PTT call set-up delay is approximately equal each instance a user presses a PTT switch in a PTT communication exchange. Thus, there is an opportunity to reduce the average PTT call set-up delay for a party who is responding to a voice communication in an on-going PTT communication exchange.
The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Drawings and accompanying Detailed Description.